CONSTITUTION AND DEVELOPMENT OF TERMITES. 11 



the body exceeds 2"5 mm. in length_, and the eight Malpighian 

 tubules have become similar. 



In general. Protozoa may be said to make their earliest 

 appearance in the large-headed forms both of Termes and 

 Caloterraes, at a time when the Malpighian tubules are 

 evidently divisible into two groups, large and small. 



If we disregard the absence of Protozoa in the very young 

 larvae, they may be said constantly to be present in the winter, 

 when the insect development is arrested, in all members of the 

 community except the complementary or substitute forms, and 

 to be then very abundant in the soldiers and workers, some- 

 what less so in the larvae and nymphs, and scarce in the true 

 kings and queens. I should add that they are found, usually 

 in small numbers, in every winged example which leaves the 

 nest. 



In summer the Protozoa are somewhat differently distributed 

 on account of the frequent ecdyses of the Termites, before 

 each of which they die off, to be subsequently re-acquired. 



That Protozoa are absent in the complementary or substitute 

 forms is a fact that has been verified in hundreds of cases. 

 But it is apparently contradicted by the following obser- 

 vations : 



1. A certain number of Protozoa were found in queens 

 of Termes lucifugus, evidently of great age, as their 

 shrunken ovarian tubes and empty spermatheca showed. 

 That these examples had certainly borne eggs was demon- 

 strated, firstly, by the presence of a granular yellowish sub- 

 stance, never found in examples which have not oviposited, 

 and situated at the mouth of the ovarian tubes in the oviducts ; 

 and secondly, by the similarity in condition of the upper and 

 lower ovarian tubes, the former being always much the smaller 

 in virgin examples. 



3. Whenever Protozoa were present in any numbers in a 

 substitute king or queen of Calotermes, the host was found to 

 be depauperised (e. g, by infestation with acari), and exhibited 

 an imperfect development of the testes or ovaries. 



